The Inon Manual stated in water with 28mm ( 35mm film equivalent ), 100.8 degrees. On land/air is 179 degrees.IF with additional Inon Dome Lens : http://marinecamera....n_domelens.html it is said 179 degrees can be achieved in water.

Once you put the dome on the lens is not useable on land as fisheye anymore

Thanks for the link, I never read that Dome info, me not interested to get a dome.

Here is what the User Manual that comes with the lens printed, I guess they have to update it he he he."Almost same view angle underwater as in AIR " but 179 - 144.8 = 34.2 degress lesser is A LOT !!! ha ha ha ha.Overall I am happy, except for the weight of the Inon bug eye though, 575 grams.

The land shot is very wide for this Inon bug eye.

Attached Images

The dome port only restores the original angle of coverage from the WA lens when it is above water, so it should be 179 deg or whatever you have measured above water. Anyway, even if it is less, I am not sure you will miss much of it, since that last 34 deg of coverage are squeezed so small to the side that the actual image in front of you is only a bit smaller.

The dome port only restores the original angle of coverage from the WA lens when it is above water, so it should be 179 deg or whatever you have measured above water. Anyway, even if it is less, I am not sure you will miss much of it, since that last 34 deg of coverage are squeezed so small to the side that the actual image in front of you is only a bit smaller.

This is a wet lens not a sealed dome. The back of the lens still remains wet so you can't just estrapolate as if it was a fisheye behind a dome port

This is a wet lens not a sealed dome. The back of the lens still remains wet so you can't just estrapolate as if it was a fisheye behind a dome port

The dome unit is not a wet lens. It has to be attached to the wet lens UWL-H100 above water with hex bolts and o-rings so the front lens element of the UWL-H100 stays in contact with air instead of water.

The dome is sealed but the lens remains wet as there is still a air-water-glass-air boundary on the back

So even if you have a dome on the lens, the lens itslef remains a wet lens and you can't do the same calculations as the interface between the port and the back of the lens still needs to be accounted for.

You can't interpolate that as the lens on land is 179 it will stay like that in water because the combination of camera and lens is not behind a dome. Besides the 179 referer to the lens without dome, the dome itself has no purpose on land. Also once you put the dome the lens performance on land deteriorates so you can't really use it

Am not sure if this is clear to you but maybe you can have a look at flat port theory?

The dome unit is not a wet lens. It has to be attached to the wet lens UWL-H100 above water with hex bolts and o-rings so the front lens element of the UWL-H100 stays in contact with air instead of water.

The dome is sealed but the lens remains wet as there is still a air-water-glass-air boundary on the back

So even if you have a dome on the lens, the lens itslef remains a wet lens and you can't do the same calculations as the interface between the port and the back of the lens still needs to be accounted for.

You can't interpolate that as the lens on land is 179 it will stay like that in water because the combination of camera and lens is not behind a dome. Besides the 179 referer to the lens without dome, the dome itself has no purpose on land. Also once you put the dome the lens performance on land deteriorates so you can't really use it

Am not sure if this is clear to you but maybe you can have a look at flat port theory?

The UWL-H100 is an afocal lens and its rear element does not converge the outgoing light, thus its interaction with the flat lens port will still be the same whether you have the dome add-on or not. Its afocal

The dome added to the front of the lens will affect how the front element of the UWL-H100 interact with the incoming light and how the light bends when it transitions to the glass.

The flat port will magnify the image by 33% due to the different medium on either side of the glass port (light going from water to air medium), but it gets negated by the rear element on the wet lens (where the light goes from air to water medium). The wet lens' front element with its water/air medium puts the magnification back to 33%.

I don't think you can and am not convinced by the explanation of lwang
It is not the flat port that magnifies is the water
so that thin layer of water between the back of the lens and the port does something, although little but it does have an effect
You can take the lens in a swimming pool and put it close to your mask you see that as it gets close things get better but it is never going to be exaclty the same as if you had the whole of the lens inside the mask
If the dome was restoring the field of view in total Inon would declare 179 not 144.8 I guess
Either way 144.8 is plenty of fov equivalent to a 7mm behind a dome and is border line of what you can light up with two strobes I would not be concerned too much

You can take the lens in a swimming pool and put it close to your mask you see that as it gets close things get better but it is never going to be exaclty the same as if you had the whole of the lens inside the mask

Now you are describing something completely different. The flat port or mask are just plane glass that causes light to bend more, but does not focus them into an image. It is the lens that converges the light to a focal point.

When you pull the lens away from your eyes, the image you observe will be less optimal. This doesn't have to do with more water in between. It has to do with the exit pupil and its limitation on the distance it can be from the nodal point of the focusing lens. You can see this when you pull it away from your eyes and seeing more distortion on the non-centered part of the image. Also when you mount the lens and zoom in your camera to its telephoto range, you will notice extreme distortion like a lens baby. The nodal point shifts further away from the front element when zooming the lens to its telephoto range.

I think how wide the lens could cover all depends on how close the rear element could come to the flat port and how close the camera's front lens element comes to the other side of the port.

OK we are not connecting here maybe my example was not the best but you should get the point anyway

There is a layer of water between the port and the wide angle lens.
The lens remains a wet lens, you can reduce that layer but still there is water in between so you can't consider the lens as if it was enclosed with the camera in a dome.
So you can't extrapolate field of view as you did as that will not be correct

Well, Inon just release another wide angle lens, the UWL-S100. This is design for zoom camera that's wider than 28mm. The description is not very clear as I believe it's translate from Japanese. The FOV is also 100, but with a dome, its FOV will be 150 underwater. So this will be similar with the UWL-H100, however, I'm wondering what's the weight of the UWL-S100 + dome. So would the UWL-S100 solve all of you guys problem?

I am sure I can re-use my AD lenses, even with the image quality of the UWL-H100 is better than my old UWL-105AD I will stick with this latter as it is only 142grams in water against the 332grams of the LD lens

There is a layer of water between the port and the wide angle lens.The lens remains a wet lens, you can reduce that layer but still there is water in between so you can't consider the lens as if it was enclosed with the camera in a dome.So you can't extrapolate field of view as you did as that will not be correct

The water layer between the rear element of the wet lens and flat port is constant with or without the dome port, their distance remains the same, so the optical effect caused by the water will be constant.

Since these are afocal lens, it will present a smaller image to the flat port/camera's lens. If your camera has a zoom lens with its shortest setting at 50mm (35mm equiv), it will not be able to capture the side of the presented image, thus you will have a narrower field of view of maybe 130 deg above water. I have the UWL-100, which is described as having a 158 deg field of view above water, but looking through it, it is obvious that I can see objects directly to the side of the lens, but the combination of its exit pupil, the camera's lens distance to the rear element and my camera's widest zoom setting, the specified field of view would be only 158 deg.

Lenses like the UWL-100 28M76 has a larger rear element, thus a wider exit pupil, which would be suitable to cameras lenses with a wider field of view such as a 28mm lens, or ones that does not use internal zooming, thus causing the front element of the lens to be farther away from the wet lens when zoomed wide.

Well, Inon just release another wide angle lens, the UWL-S100. This is design for zoom camera that's wider than 28mm. The description is not very clear as I believe it's translate from Japanese. The FOV is also 100, but with a dome, its FOV will be 150 underwater. So this will be similar with the UWL-H100, however, I'm wondering what's the weight of the UWL-S100 + dome. So would the UWL-S100 solve all of you guys problem?

The UWL-S100 is made for superzoom cameras that does not use internal zooming, So when your camera is zoomed to full wide, you will get circular fisheye effect given the UWL-S100's small pupil exit diameter and the far distance of the front element of the zoom lens and the wet lens. In order to eliminate that effect, one has to zoom the lens to 80mm (35mm equiv), so that it can capture the full image presented by the wet lens.

I am good with the considerations around the zoom but you can't assume that putting a sealed dome on a wet-lens give you the air field of view regardless of the zoom as that stays the same and is well inside the housingWhat creates the difference is that thin layer of water that will still have diffraction. In order to have the same field of view in air you would need to seal it

For what concerns field of view and vignetting the consideration is the size of the lens in front of the camera and the distance between the front lens and the glass at the required zoom setting.

The RX100 at the widest setting is actually at the same distance from the glass than in telephoto so it is an ideal condition not to vignette at 28MM in fact I am pretty sure that the UWL100 28AD will not vignette and that the UWL100 will stop vignetting pretty soon around 32mm. I have this camera so I can tell you that is the case and you can check it hereAt 35mm the difference in the distance lens port is only another 1.5mm

I am going into the pool this wednesday and I will test both lenses I have from the tests on land I can tell you the behaviour is the same of the Canon S95 that is a 28mm equivalent with a 1/1.7 sensor on my tests on land

Although the best quality is probably with the UWL-H100 that require no zoom the RX100 with the right adapter can probably work with any Inon wide lens

For video specifically when you use the active steady shot there is some sensor cropping and an equivalent length of 33mm, I bet it does not vignette at all with an UWL100 at the widest zoom